Ocean Worlds Exploration and Autonomy Decadal Survey 2023-2032 Development of Autonomous Actions to Enable the Next Decade of Ocean World Exploration Corresponding Author: Glenn E. Reeves, Jet Propulsion Laboratory (JPL), California Institute of Technology, [email protected] Co-Authors: Brett A. Kennedy (JPL), Grace H. Tan-Wang (JPL), Paul G. Backes (JPL), Steve A. Chien (JPL), Vandi Verma (JPL), Kevin P. Hand (JPL), Cynthia B. Phillips (JPL) This work was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (80NM0018D0004). © 2020. California Institute of Technology. Government sponsorship acknowledged Pre-Decisional Information — For Planning and Discussion Purposes Only CL#20-3666 Ocean Worlds Exploration and Autonomy Decadal Survey 2023-2032 1. Executive Summary The development of autonomous actions aboard surface systems is of great value to the exploration of ocean worlds, and the in situ exploration of much of our solar system. The ability of landers to operate with more autonomy than current landers and rovers will enable more and better science, with an overall reduction in cost for comparable missions. In this paper we identify the array of challenges that confront in situ exploration on an ocean world and how many of these challenges are, and have been, addressed (and in some cases resolved) in the early development work for NASA’s Europa Lander mission concept. We identify the pathway for constructing a highly autonomous surface system that enables ocean worlds exploration across an array of targets. Our key developments include: • A system-wide architecture effort to identify the mission activities, and the onboard decisions, that will be required for time- and resource-efficient missions. This activity identifies the onboard autonomous behaviors and the necessary supporting architecture, such as the sensing required. A holistic approach to autonomy overall is the intent, including identifying computation needs, strategies for the judicious use of energy, applicability of multiple methods for sample acquisition, fault and failure reaction strategies, learning options from surface interactions, and self-calibration and assessment techniques. • A focused investigation of the autonomy related to sample acquisition, including mechanism and end-effector tool development, the development of representative algorithms for workspace assessment, sample/excavation target identification, dynamic tool use/control, and sensing needed to ascertain acquisition success. This investigation also includes adaptation based on surface interactions. • The construction of both a hardware-in-the-loop (HITL) testbed and a software-plus-simulation (“SoftSim”) testbed environment to enable the implementation of multiple “prototype” “systems”. The testbed environments will have both the fidelity and flexibility to represent the trade space for the most challenging tasks related to autonomous functionality. • The exploration of onboard versus ground operator responsibility for mission activities. The uncertainties of the surface environment, and the influence of operators/scientists in the execution of the specific activities, deserves consideration and experimentation. The proper mix will vary with the mission target, but all are likely to need to balance the amount of science and engineering data for a given uplink or downlink opportunity to maintain a compelling operational tempo. (Europa allows a relatively low direct-to-Earth communications link for about 50% of a 86 hour europan day.) • An exploration of autonomy enabling architectural and design choices for the surface spacecraft. A surface mission with significant autonomy goals will require expanded resiliency by design, spanning from sensing and perception to alternative strategies to accomplish the required mission activities. Less visible, but still critical to autonomous behaviors, will be sufficient computation, sufficient memory and storage, and effective fault/interruption detection. Designing a system with fewer resource limitations may be the right trade to reduce the overall complexity of implementation. © 2020. California Institute of Technology. Government sponsorship acknowledged Pre-Decisional Information — For Planning and Discussion Purposes Only CL#20-3666 Ocean Worlds Exploration and Autonomy Decadal Survey 2023-2032 • An exploration of how to achieve the continuation of activities even in the presence of interruptions of functionality or failures due to the environment. 2. Introduction The robotic exploration of our solar system can be significantly enhanced through the development and implementation of autonomy for many aspects and phases of mission operations. Autonomy can be used to increase the operational efficiency of a mission, helping to conserve engineering resources while simultaneously increasing the science return of a mission. From sampling on the surfaces of Venus and Ocean Worlds, to acquiring data during the flyby of a Kuiper belt object, many science goals and mission targets will benefit from developments and investments in autonomy. On Venus, the harsh temperature and pressure of the surface impose a limit on the lifetime of a landed vehicle, making autonomy an attractive answer to acquiring and processing samples. On Ocean Worlds such as Europa and Enceladus, planetary protection concerns and mission cost and complexity could make radioisotope power sources less attractive, leading to some shorter lived missions that operate with primary batteries. Such missions would also benefit significantly from elements of autonomous operations. Finally, efforts to deploy low-cost missions that fly-by, orbit, or even land on worlds throughout our Solar System will be enabled by the ability to autonomously achieve targeted science and execute ranked onboard operations. Here we highlight developments in autonomy that have been made possible as part of the 2016-2020 Europa Lander Mission Concept. We also detail areas for future development and investment. Though our description focuses on the specific case of the Europa Lander mission concept, these advancements can be applied to many other ocean worlds and planetary missions. 3. What is ‘autonomy’? Here we define autonomy as the ability of a vehicle to achieve the mission goals while operating independently of external control. At the same time, the vehicle must perceive and react when presented by the uncertainties of interacting with Europa (or any other world). Autonomy must include both the ability to self-direct, and the self-sufficiency needed to operate independently. The overall system that achieves these characteristics must be designed from conception to support autonomy. Autonomy and the Europa Lander Mission Concept We refer the reader to the Europa Lander Study 2016 Reporti for background information on the Europa Lander science and the mission concept. The baseline Europa Lander mission concept employs onboard autonomy to efficiently collect and analyze samples, and then transmit prioritized information to Earthii. Figure 1 shows some examples of specific systems under development for surface operations. Importantly, operational efficiency and urgency is only one of a number of challenges that an in situ mission at Europa, or any ocean world, would be required to address. The use of autonomy is an obvious architectural solution to many of the challenges, but our © 2020. California Institute of Technology. Government sponsorship acknowledged Pre-Decisional Information — For Planning and Discussion Purposes Only CL#20-3666 Ocean Worlds Exploration and Autonomy Decadal Survey 2023-2032 ability to truly capitalize on its promise requires an encompassing examination of the challenges and required capabilities of the eventual system. This is not a simple reapplication of prior techniques, nor is it sufficient to assume that there is direct relationship to strategies used in other in situ missions. Although a spacecraft that must operate on the surface of Europa faces similar challenges that spacecraft on Mars may have addressed, Europa isn’t Mars, and there are unique challenges that amplify the critical need for onboard autonomous capabilities. The Europa Lander pre-project has assessed those challenges and is in the process of building the strategies, techniques, framework, and tools to apply to the developmentiii. Pre-Project Advanced Development for Autonomy The Europa Lander pre-project is a mature concept that has been evolving since the Mission Concept Review1 with project funds for advanced development work in autonomy and other areas. This effort is multifaceted as it is intended to advance the maturity of the specific technology, architecture, and design challenges. The Europa Lander pre-Project is funded to investigate the breadth and scope of the autonomous capabilities potentially needed to ensure a successful surface mission phase. 4. Motivations and Solutions for Autonomous Operations • Surface Uncertainty: The spacecraft would land on the surface of Europa with surface knowledge at a scale larger than what will be needed for sample acquisition (meters versus centimeter). Since the surface topography and the specific material properties of the surface material would have a significant understanding uncertainty prior to landing, the spacecraft must be designed for a range of possible scenarios, and the system must be able to autonomously adapt as required. o Advanced Developments